R09 - December, 2011 - Regular Examinations - Set - 2.
B.Tech II Year - I Semester Examinations, December 2011
ELECTRONIC DEVICES AND CIRCUITS
(COMMON TO EEE, ECE, CSE, EIE, BME, IT, MCT, E.COMP.E, ETM, ICE)
Time: 3 hours Max. Marks: 75
Answer any five questions
All questions carry equal marks
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1.a) What do you understand about the depletion region at a PN junction, with the help of necessary diagrams and derive expression for barrier potential.
b) Derive the expression for transition capacitance, CT of a PN diode. [9 6]
2.a) With neat sketches explain the operation of a FWR with L- section filter & derive the expression for its ripple factor. Also explain the necessity of a bleeder resistor in a practical L- section filter.
b) Determine the ripple factor of an L-section filter comprising a 10H choke and 8µF capacitor, used with a FWR. The DC voltage at the load is 50V. Assume the line frequency as 50Hz. [10 5]
3.a) Draw the circuit diagram of NPN transistor in Common Emitter(CE) configuration. With neat sketches and necessary equations, describe its static input-output characteristics and clearly indicate the cut-off, saturation & active regions on the output characteristics?
b) Calculate the values of IC and IE for a transistor with adc = 0.99 and ICBO = 5µA, if IB is measured as 20 µA. [10 5]
4.a) What do you mean by biasing a transistor? Explain the need of biasing a transistor for the construction of a faithful amplifier?
b) Design a collector to base bias circuit using silicon transistor to achieve a stability factor of 20, with the following specifications: VCC = 16V, VBE = 0.7V, VCEQ = 8V, ICQ = 4 mA & ß= 50. [7 8]
5.a) In the amplifier circuit shown in Figure.1, estimate input resistance and voltage gain? Also derive the expressions used?
Figure.1
b) Compare CB, CE and CC amplifiers with respect to AV, AI, RI & RO? [10 5]
6.a) Explain the construction & operation of a P-channel MOSFET in enhancement and depletion modes with the help of static drain characteristics and transfer characteristics?
b) In an n-channel FET, the effective channel width is 3x 10-4cm and the donor impurity concentration is 1015 electrons/cm3. Find the pinch-off voltage? [10 5]
7.a) Draw the basic circuit and small-signal model of Common Drain FET amplifier. Derive expressions for voltage gain and output resistance?
b) Compare the merits & demerits of a Bipolar Junction Transistor (BJT) with Field effect Transistor (FET) in detail? [8 7]
8.a) Draw the firing characteristics of SCR and briefly explain it.
b) Define the following with respect to SCR
i) Forward break over voltage
ii) Reverse break over voltage
iii) Holding current
iv) Gate trigger current. [7 8]
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ELECTRONIC DEVICES AND CIRCUITS
(COMMON TO EEE, ECE, CSE, EIE, BME, IT, MCT, E.COMP.E, ETM, ICE)
Time: 3 hours Max. Marks: 75
Answer any five questions
All questions carry equal marks
---
1.a) What do you understand about the depletion region at a PN junction, with the help of necessary diagrams and derive expression for barrier potential.
b) Derive the expression for transition capacitance, CT of a PN diode. [9 6]
2.a) With neat sketches explain the operation of a FWR with L- section filter & derive the expression for its ripple factor. Also explain the necessity of a bleeder resistor in a practical L- section filter.
b) Determine the ripple factor of an L-section filter comprising a 10H choke and 8µF capacitor, used with a FWR. The DC voltage at the load is 50V. Assume the line frequency as 50Hz. [10 5]
3.a) Draw the circuit diagram of NPN transistor in Common Emitter(CE) configuration. With neat sketches and necessary equations, describe its static input-output characteristics and clearly indicate the cut-off, saturation & active regions on the output characteristics?
b) Calculate the values of IC and IE for a transistor with adc = 0.99 and ICBO = 5µA, if IB is measured as 20 µA. [10 5]
4.a) What do you mean by biasing a transistor? Explain the need of biasing a transistor for the construction of a faithful amplifier?
b) Design a collector to base bias circuit using silicon transistor to achieve a stability factor of 20, with the following specifications: VCC = 16V, VBE = 0.7V, VCEQ = 8V, ICQ = 4 mA & ß= 50. [7 8]
5.a) In the amplifier circuit shown in Figure.1, estimate input resistance and voltage gain? Also derive the expressions used?
Figure.1
b) Compare CB, CE and CC amplifiers with respect to AV, AI, RI & RO? [10 5]
6.a) Explain the construction & operation of a P-channel MOSFET in enhancement and depletion modes with the help of static drain characteristics and transfer characteristics?
b) In an n-channel FET, the effective channel width is 3x 10-4cm and the donor impurity concentration is 1015 electrons/cm3. Find the pinch-off voltage? [10 5]
7.a) Draw the basic circuit and small-signal model of Common Drain FET amplifier. Derive expressions for voltage gain and output resistance?
b) Compare the merits & demerits of a Bipolar Junction Transistor (BJT) with Field effect Transistor (FET) in detail? [8 7]
8.a) Draw the firing characteristics of SCR and briefly explain it.
b) Define the following with respect to SCR
i) Forward break over voltage
ii) Reverse break over voltage
iii) Holding current
iv) Gate trigger current. [7 8]
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CreatedSep 29, 2012
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UpdatedSep 29, 2012
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